From the Eugene area, head up Hwy99w. About 1/2 mi north of Monroe turn left (West) and follow the signage for Alsea Falls Campground (about 14mi). Just after the campground, you can park in the Day use area. This makes it a nice ~3.5mi round trip hike. Alternatively, you can continue on to Hubert K. McBee Memorial Park. The falls is only a mile hike (r/t) via this avenue.
Although the path can be a little narrow at times due to a little overgrowth, this is was nice family trek (including grandkids).
The trail starts at the North side of the Alsea Falls day use area ($3/fee). Cross over the footbridge to the north side of the river and turn left (it’s signed once over the bridge). After a short walk, there is a wooden staircase that heads down to Alsea Falls which you can see partly from the path you’re on.
Keep the creek on your left at any junctions. Pretty soon the trail empties onto an old gravel logging road. When the road forks, stay right and follow it as it slowly rises (going to the left is a dead-end/turnaround but has a nice stand-at table cut from an old log that’s about 40′ long and 2′ wid). As you descend, you’ll pass the entrance to McBee Park / campsite#4 which goes over a concrete bridge. Bypass the bridge/campsite. Pretty soon you’ll come across another campsite on the right (just before passing over an OLD concrete bridge that’s only 20′ long). At the far end of that campsite you’ll see a small hiking sign which is the continuation of the hiking trail to Green Peak Falls.
Once you’re on the trail again, stay to the left and you’ll notice the creek has reversed directions from the first part of the hike (you’re now seeing Peak Creek). Watch out for hard, loose dirt as parts of the trail get a little slippery at times.
Once at Green Peak Falls, you’ll notice a steep scramble on the right that leads to the top of the falls. The creek at the top during August is shallow and slow moving.
The rocks leading to the base of the main falls are very slippery.. Be sure to watch out for Salamanders too. The lower part of the falls (only bout a 6′ cascading drop) are nice to relax and sit in.
There was only a small portion of the width of the upper falls on our trip but during higher water months, the falls cascade over almost the entire rock area and there’s a lot less chance to actually be in the falls.